interface CompurerAverage{
public double average(double a,double b);
}
class A implements CompurerAverage{
	public double average (double a,double b) {
	double aver =0;
	aver=(a+b)/2;
	return aver;
	}
}

class B implements CompurerAverage{
	public double average (double a,double b) {
	double aver =0;
	aver=Math.sqrt(a*b);
	return aver;
	}
}
public class p153{
public static void main(String args[]) {
	CompurerAverage computer;
	double a=11.23,b=22.78;
	computer =new A();
	double result=computer.average(a,b);
	System.out.printf("%5.2f和%5.2f的算数平均根：%5.2f\n",a,b,result);
	computer=new B();
	result=computer.average(a,b);	
	System.out.printf("%5.2f和%5.2f的几何平均根：%5.2f\n",a,b,result);
	}
}
